vlib/v/checker/tests/os_prefix.vv:1:8: warning: module 'os' is imported but never used
    1 | import os
      |        ~~
    2 | 
    3 | fn main() {
vlib/v/checker/tests/os_prefix.vv:5:12: error: unknown function: execute
    3 | fn main() {
    4 |     cmd := 'ls'
    5 |     result := execute(cmd)
      |               ~~~~~~~~~~~~
    6 |     println(result)
    7 | }
vlib/v/checker/tests/os_prefix.vv:5:9: error: assignment mismatch: 1 variable but `execute()` returns 0 values
    3 | fn main() {
    4 |     cmd := 'ls'
    5 |     result := execute(cmd)
      |            ~~
    6 |     println(result)
    7 | }
vlib/v/checker/tests/os_prefix.vv:6:2: error: `println` can not print void expressions
    4 |     cmd := 'ls'
    5 |     result := execute(cmd)
    6 |     println(result)
      |     ~~~~~~~~~~~~~~~
    7 | }
